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County · code 17065

Hamilton CountyIllinois

Hamilton County is a county in Illinois with its seat in McLeansboro, formed in 1821.

  • Founded1821
  • County seatMcLeansboro
  • Named forAlexander Hamilton
  • Land area435 sq mi + 1.2 sq mi water
  • Population7,993 2020 Census
  • Parcels mapped10,507 checked 16 October 2026
Open the free map Click any parcel in Hamilton County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

SalineWhiteGallatin McLeansboro Census outline · seat marked

Where it is

Hamilton on the map of Illinois

Illinois has 102 counties and county equivalents, each with its own records office. Shapes with a page are links.

Adams CountyAlexander CountyBond CountyBoone CountyBrown CountyBureau CountyCalhoun CountyCarroll CountyCass CountyChampaign CountyChristian CountyClark CountyClay CountyClinton CountyColes CountyCook CountyCrawford CountyCumberland CountyDeKalb CountyDe Witt CountyDouglas CountyDuPage CountyEdgar CountyEdwards CountyEffingham CountyFayette CountyFord CountyFranklin CountyFulton CountyGallatin CountyGreene CountyGrundy CountyHancock CountyHardin CountyHenderson CountyHenry CountyIroquois CountyJackson CountyJasper CountyJefferson CountyJersey CountyJo Daviess CountyJohnson CountyKane CountyKankakee CountyKendall CountyKnox CountyLake CountyLaSalle CountyLawrence CountyLee CountyLivingston CountyLogan CountyMcDonough CountyMcHenry CountyMcLean CountyMacon CountyMacoupin CountyMadison CountyMarion CountyMarshall CountyMason CountyMassac CountyMenard CountyMercer CountyMonroe CountyMontgomery CountyMorgan CountyMoultrie CountyOgle CountyPeoria CountyPerry CountyPiatt CountyPike CountyPope CountyPulaski CountyPutnam CountyRandolph CountyRichland CountyRock Island CountySt. Clair CountySaline CountySangamon CountySchuyler CountyScott CountyShelby CountyStark CountyStephenson CountyTazewell CountyUnion CountyVermilion CountyWabash CountyWarren CountyWashington CountyWayne CountyWhite CountyWhiteside CountyWill CountyWilliamson CountyWinnebago CountyWoodford CountyHamilton County Hamilton
Counties of Illinois · Hamilton highlighted

History

Formed in 1821 from White County

An old deed may name a county that no longer exists, or a boundary that has since moved.

Hamilton County was created from White County on February 8, 1821, and named after Alexander Hamilton. On November 7, 1854, Hamilton County gained territory from Saline County.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries.

  1. 1821
    Hamilton County created Hamilton created from White.
    from White
    · Ill. Laws 1820-1821, pp. 113-114
  2. 1854
    Gained territory Hamilton gained from Saline.
    from Saline
    · History of Gallatin, Saline, 42-43; Ill. Laws 1853, gen., pp. 265-266; Ill. Laws 1854, priv., pp. 143-144

Land and parcels

What the maps cover in Hamilton

Who publishes each layer, how good it is, and when we last checked.

Official
from the office that keeps the record
Good enough
a reliable statewide or national copy
Fallback
a guide only; check the official record
Missing
nothing public found yet

People and land

Hamilton by the Census

Population
7,993 2020 Census count
Housing units
3,806 2020 Census count
Land area
435 square miles
Water area
1.2 square miles
People per sq mi
18 population ÷ land area

Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.

Rules and offices

Who to ask before you build, dig or sell

Official county pages only. We link to them; we do not copy them, because they change.

Inside a city or town, permits usually come from that city rather than the county.

Zoning and code

County government

See your own lot on these maps

Open Hamilton County on Parcel Chart's free map and click your parcel. Save it with a free account; the full record of your place (site map, projects, documents) is Pro, in early access.

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Questions

Common questions about Hamilton County

When was Hamilton County founded?
Hamilton County was founded in 1821, formed from White County, and named after Alexander Hamilton.
What is the county seat of Hamilton County?
The county seat of Hamilton County is McLeansboro.
Is there an online parcel map for Hamilton County?
Yes. Hamilton County publishes a parcel map of 10,507 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Hamilton County's boundary or name changed?
Hamilton County was created in 1821 from White County. Since then the Atlas of Historical County Boundaries records 1 later change, chiefly involving Saline County.
Is my lot in a flood zone?
We do not have flood maps for Hamilton County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby

Counties next door